[402] A need arose
during the Vietnam conflict for a specialized aircraft capable of
giving close air support to troops operating in the forward battle
area. Needed was a heavily armed aircraft that could respond
rapidly to a call for help and had the ability to destroy tanks,
artillery batteries, and other types of enemy strongholds. Neither
a fast aircraft nor one with long range was required; good
maneuverability, extended loiter time in the battle area, and a
lethal weapons load were needed. Low cost, easy maintenance with
minimum turnaround time, and high survivability in the face of
enemy ground fire were other characteristics desired. The aircraft
was intended only for daytime operations in fair weather.

Detailed requirements for such a
close-air- support aircraft were issued by the USAF in May 1970.
Fairchild- Republic and Northrop were given contracts for the
construction of prototypes to be used in a flyoff competition from
which a winner would be selected for production.
Fairchild-Republic with its A-10A was declared the winner in
January 1973. First flight of the aircraft occurred in May 1972,
and the first squadron to be equipped with the A-10A became
operational in October 1977. The aircraft is still in production
with a planned output of over 700 units.

[403] The A-10A,
dubbed the Thunderbolt II, is shown in figures
12.28and 12.29. Configuration of the Thunderbolt II is
like that of no other modern aircraft and, in some respects, seems
to be a throwback to an earlier aeronautical age. The unswept wing
is tapered only slightly and is mounted near the bottom of the
flat-sided fuselage, about midway between the nose and the tail.
Airfoil sections vary in thickness ratio from 16 percent at the
root to 13 percent at the tip. An aft-loaded camber line is used
in the airfoil sections to improve turning performance at low
speeds in the battle area. In effect, this camber line acts like a
flap with a small permanent deflection. A single-slotted
trailingedge flap is provided, and ailerons are used for lateral
control. For aerodynamic braking, the upper and lower surfaces of
the ailerons separate and deflect above and below the wing.

Two General Electric turbofan engines are
contained in separate nacelles that are pylon mounted slightly
above and to either side of the fuselage and behind the wing. The
horizontal tail is below and to the rear of the engines; the
vertical surfaces are at the tips of the horizontal tail outboard
of the engines. Serious exhaust impingement on both the...

....horizontal and vertical surfaces is
avoided by this arrangement. Conventional elevators and rudders
are provided for pitch and yaw control, respectively.
Main-landing-gear units retract into fairings below the wing, and
the single nose-wheel gear is offset to facilitate optimum
location of the offensive cannon. The single pilot's cockpit is
near the nose of the fuselage and is equipped with a zero-zero
ejection seat. (A successful escape can be made at zero altitude
and speed.) Protection of the cockpit area is provided by an
armored "bathtub" constructed of titanium said to be able to
withstand the impact of projectiles of up to 23 mm in size.

Primary armament of the A-10 is a large
30-mm seven-barrel rotary cannon. This impressive weapon can fire
at a rate of either 2100 or 4200 rounds per minute. Equipped with
1950 rounds of ammunition, the gun weighs 4041 pounds; its empty
weight is 1975 pounds. The gun is positioned in the nose so that
the firing barrel is always located on the centerline of the
aircraft. Muzzle of the cannon may be seen protruding from the
nose in figures 12.28 and 12.29. In addition to the formidable
30-mm cannon, four store-mounting stations are [405] provided under
each wing and three are located beneath the fuselage. A wide
assortment of different stores can be carried on the aircraft.
With full internal fuel tanks, the maximum external load is a
remarkable 14 341 pounds.

The data in table VI show a maximum gross weight of 40 269 pounds for
the Thunderbolt II. With a payload of 9540 pounds, mission radius
is 288 miles, including a 2-hour loiter period on station. Ferry
range with no payload and maximum external fuel is 3510 miles. At
a cruising speed of 329 miles per hour, time required for the
single pilot to fly this distance is a little over 10 hours.
Certainly a fatiguing flight, but not a remarkably long one for a
single pilot. Maximum speeds for the A-10A given in table VI are comparable to those achievable by the fastest
propeller-driven fighters of World War II.

Certainly the Thunderbolt II (sometimes
irreverently referred to by crew members as the Warthog) will
never reap any honors for ascetic appeal. Yet, given its unique
mission requirements, a more practical design is difficult to
envision. Its ultimate usefulness in a combat situation, however,
has yet to be proven.